Heat large wok (or large frying pan with high sides) on high heat until drop of water sizzles on contact. Add 1 teaspoon peanut oil and spread oil around bottom of wok with spatula. Add shrimp, season with salt, and stir-fry until they turn pink but are not completely cooked through, 1 to 2 minutes. Transfer to plate.

Add remaining 1 tablespoon peanut oil to wok and spread oil with spatula. Add ginger and cook for about 30 seconds to release its fragrance, then add bok choy stems, garlic and chile. Stir-fry, adjusting heat to prevent scorching, until bok choy begins to soften, 2 to 3 minutes. If stems are quite thick, you may need to add 1 or 2 tablespoons of water and cover wok briefly to complete the cooking, but do not overcook.

Stir oyster sauce mixture to recombine. Add to wok along with bok choy leaves. Stir-fry until leaves begin to wlt, less than a minute, then add shrimp and stir-fry until fully cooked.